It is known in building systems technology to use switches to switch electrical consumers. For this purpose, at least one power contact of a building power network is switched to the electrical consumer. For example, an electric lighting unit in the building is switched on, or off or dimmed by means of a manual switch.
DE 44 258 76 A1 demonstrates a power outlet with an integrated network node and a current supply of the network node with the aim of increasing the functionality. The network node communicates via a building power network in a bus system and, in response to commands from a higher level control center, switches a relay in the power outlet. Electrical consumers connected to the power outlet are thus switched by the central control. The building power network serves both to supply the electrical consumers with electrical current and also to allow the network node and the control center to communicate with each other via the bus system.
With the aim of providing an uncomplicated communications standard which can be adapted to suit the most varied conditions, the short-range communications standard ZigBee (IEEE 802.15.4) has been developed in accordance with http://standards.ieee.org/getieee802/download/802.15.4-2003.pdf. According to this short-range communications standard ZigBee (IEEE 802.15.4) a command is transmitted to switch the electrical consumer via a radio network which is separate from the building power network. It is true that only small quantities of data from 20 to 250 Kb/s can be transmitted over short distances of less than 300 meters, but in view of the teaching of DE 44 258 76 A1 the short-range communication has the advantage that temporal and local changes in the impedance behavior of the building power network cannot lead to disruptions to communications.